optimal quality yuv to rgb conversion in premiere

[codemaster]

I use the Lagarith codec to losslessly compress some decoded mpg clips (decoded with DGDecode and processed with some filters in AviSynth).

Before I import the avi clips in Premiere Pro CS3, I have two options:
1. I can convert from YUV to RGB in AviSynth, after processing with filters, and before compressing to Lagarith in RGB mode using VirtualDub.
2. I can leave the avs script in YUV, and compress to Lagarith in YV12 mode with VirtualDub (fast recompress), and then import the avi clips in Premiere Pro and let Premiere convert from YUV to RGB.

The advantage of option #2 is that the avi files will require less hdd space. But can AviSynth do a better quality YUV to RGB conversion than Premiere Pro can ? Better enough that it justifies editing with much larger RGB avi files ?

[sanlyn]

Avisynth is better and more precise, and resizes better as well. Why not use the Avisynth plugin for Adobe Premiere?
http://neuron2.net/www.math.berkeley.edu/benrg/avisynth-premiere.html

[codemaster]

Is Dither_convert_yuv_to_rgb() higher quality than ConvertToRGB() ?

For converting from RGB, back to YV12 (in order to use LanczosResize() filter and to frameserve to x264), is there a better quality filter than ConvertToYV12() ?

Frameserving to Premiere using avisynth premiere plugin... would be very slow... I suppose I could set QTGMC to draft, edit, and change from draft to slower after editing and before rendering... but I'm not sure this offers good stability, and it requires dependance on plugins that may not be compatible with newer versions of premiere... so using lagarith and large files would be a way to avoid compatibility issues...

[sanlyn]

Do your qtgmc, denoising, etc., in Avisynth and save that AVI with Lagarith or another lossless compressor. Then make a new script for Premiere; all that script will do is open the file, convert to RGB32, and send the video to Adobe. It's a very fast process. Premiere can read Lagarith or huffyuv AVI as long as you have the compressors installed. I do this with After Effects quite often.

The dithered version of YUV->RGB and RGB->YUV will be superior if you're dealing with material that has color banding problems or that needs resizing. Otherwise Avisynth's converters are OK and better than Adobe's.